Corn steep liquor for fermentation as well as preparation method and application of corn steep liquor

Abstract

The invention provides corn steep liquor for fermentation as well as a preparation method and application thereof, and belongs to the technical field of biology. The preparation method of the corn steep liquor for fermentation comprises the following steps: hydrolyzing corn steep liquor, homogenizing the hydrolyzed corn steep liquor, heating the homogenized corn steep liquor, and filtering to obtain the corn steep liquor for fermentation. According to the method disclosed by the invention, hydrolysis and high-pressure homogenization processes are combined, so that residual microorganisms in the corn steep liquor can be effectively cracked, meanwhile, substances such as macromolecular proteins can be decomposed into easily-utilized nutrients, the risk of bacterial contamination caused by incomplete sterilization of the corn steep liquor in a fermentation tank is reduced, and meanwhile, the conversion rate of fermentation products is increased.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and in particular relates to corn steep liquor for fermentation, a preparation method and application thereof. Background Art

[0002] Corn slurry is a byproduct of corn starch production. It contains a large amount of amino acids, vitamins and growth factors, and is a cheap organic nitrogen source. Its rich nutrients can promote cell growth, increase fermentation acid production and sugar-acid conversion rate. In the production of amino acid fermentation, corn slurry plays an important role as an organic nitrogen source and growth factor supplier in amino acid fermentation. It is rich in biotin and limiting amino acids, which can significantly affect the fermentation process of amino acids. By increasing the use of corn slurry, some organic nitrogen sources such as soybean meal hydrolyzate, yeast powder and hair powder can be reduced or replaced, thereby reducing the cost of amino acid production. Corn slurry can also be used as a high-quality feed additive and raw material to provide animals with the required nutrition. It is rich in protein, amino acids, vitamins and minerals, which can improve the nutritional content of feed and increase the palatability and nutritional value of feed.

[0003] The traditional corn slurry treatment method is hydrolysis. Although it can treat corn slurry well, a large number of microorganisms, such as Bacillus, remain in the corn slurry after treatment. The inactivation temperature of Bacillus is relatively high. At the same time, there are many impurities in the corn slurry, and the impurities contain miscellaneous bacteria. If the sterilization is not thorough during fermentation, it is easy to cause bacterial contamination and affect the fermentation level. Therefore, it is necessary to propose a new method for treating corn slurry for fermentation to solve the problem of high microbial content in corn slurry, reduce the probability of bacterial contamination in fermentation production, and improve the utilization rate of corn slurry. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a corn slurry for fermentation and a preparation method and application thereof. The present invention can effectively crack the residual microorganisms in the corn slurry, and at the same time can decompose substances such as macromolecular proteins into easily usable nutrients, thereby reducing the risk of contamination of the fermentation tank due to incomplete sterilization of the corn slurry, and at the same time improve the conversion rate of the fermentation product.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: The invention provides a method for preparing corn steep liquor for fermentation, comprising the following steps: hydrolyzing corn steep liquor, homogenizing the hydrolyzed corn steep liquor, and then heating and filtering the homogenized corn steep liquor to obtain corn steep liquor for fermentation.

[0006] Preferably, the step of hydrolyzing the corn slurry comprises: heating the corn slurry, keeping the temperature after heating, cooling the corn slurry after keeping the temperature, adding concentrated sulfuric acid, adjusting the pH to below 2.5, stirring, and obtaining a corn slurry hydrolyzate.

[0007] Preferably, the corn steep liquor is heated to 100-130° C., and the insulation time is 10-30 min.

[0008] Preferably, the corn steep liquor is cooled to 70-90°C.

[0009] Preferably, the volume ratio of the concentrated sulfuric acid to the corn steep liquor is 1:1-4.

[0010] Preferably, the homogenization conditions include: temperature 15-30°C, pressure 60-100Mpa, and feed rate 10-30L / min.

[0011] Preferably, the temperature of the homogenized corn steep liquor is raised to 70-90°C.

[0012] Preferably, the filtration pore size is 30-50 mesh.

[0013] The invention provides corn steep liquor for fermentation prepared by the preparation method.

[0014] The present invention provides application of corn steep liquor for fermentation prepared by the preparation method in preparing fermentation medium.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention combines hydrolysis and homogenization processes, which can effectively crack the residual microorganisms in the corn slurry, and can also decompose substances such as macromolecular proteins into nutrients that are easy to utilize, thereby reducing the risk of bacterial contamination in the fermentation tank due to incomplete sterilization of the corn slurry, and at the same time improving the conversion rate of the fermentation product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The left picture is the corn syrup hydrolyzate prepared in Example 1, and the right picture is the corn syrup for fermentation prepared in Example 1 of the present invention.

[0017] Figure 2 The figure is a comparison of the corn syrup state before and after homogenization. The bottle on the left is the corn syrup for fermentation prepared in Example 1 of the present invention, and the bottle on the right is the corn syrup hydrolyzate prepared in Example 1. DETAILED DESCRIPTION

[0018] The present invention provides a method for preparing corn slurry for fermentation, comprising the following steps: hydrolyzing corn slurry, homogenizing the hydrolyzed corn slurry, and then heating and filtering the homogenized corn slurry to obtain corn slurry for fermentation. The present invention first hydrolyzes the corn slurry and then homogenizes it, which can effectively crack the microorganisms remaining in the corn slurry, and can also decompose substances such as macromolecular proteins into nutrients that are easy to use, thereby reducing the risk of bacterial contamination in a fermentation tank due to incomplete sterilization of the corn slurry, and at the same time improving the conversion rate of the fermentation product.

[0019] In the present invention, the step of hydrolyzing the corn slurry comprises: heating the corn slurry, keeping the temperature after heating, cooling the corn slurry after keeping the temperature, adding concentrated sulfuric acid, adjusting the pH to below 2.5, stirring, and obtaining a corn slurry hydrolyzate.

[0020] In the present invention, the corn steep liquor is heated to 100-130° C., preferably 110-125° C., and more preferably 120° C.; the insulation time is 10-30 min, preferably 18-28 min, and more preferably 20 min.

[0021] In the present invention, during the hydrolysis of corn steep liquor, the corn steep liquor is cooled to 70-90°C, preferably 78-88°C, and more preferably 80°C.

[0022] In the present invention, the volume ratio of sulfuric acid to corn steep liquor is 1:1-4, preferably 1:1.5-3.5, and more preferably 1:2.5. The present invention increases the sulfuric acid ratio during hydrolysis and reduces pH, which is not conducive to bacterial growth.

[0023] In the present invention, the homogenization conditions include: temperature 15-30°C, pressure 60-90Mpa, feed rate 10-30L / min. The present invention forces the liquid material to pass through fine gaps through high pressure, so that the material becomes delicate and uniform under the action of high pressure and shear force. When the material passes through the homogenization valve under high pressure, shear, impact and cavitation effects will occur, so that the particles in the material are broken and the homogenization effect is achieved. The use of high-pressure homogenization can effectively crack the remaining microorganisms in the corn pulp, and at the same time can decompose substances such as macromolecular proteins into nutrients that are easy to use.

[0024] In the present invention, the temperature of the homogenized corn steep liquor is 70-90°C, preferably 78-88°C, and more preferably 80°C.

[0025] In the present invention, the filtration aperture is 30-50 mesh, preferably 35-45 mesh, and more preferably 40 mesh. The filtration in the present invention is preferably carried out by filter bag filtration.

[0026] The invention also provides corn steep liquor for fermentation prepared by the preparation method.

[0027] The present invention also provides the use of the fermentation corn steep liquor prepared by the preparation method in preparing a fermentation medium. The fermentation medium prepared by the fermentation corn steep liquor prepared by the present invention can be used for fermentation to produce lysine and isoleucine.

[0028] In the present invention, unless otherwise specified, all components, reagents or culture media are commercially available products well known to those skilled in the art.

[0029] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1 (1) The corn slurry was heated to 120°C, and then kept warm for 20 minutes. After the heating was completed, the corn slurry was cooled to 75°C. Then, 98% concentrated sulfuric acid was added in a volume ratio of 1:2.5 to corn slurry, the pH was adjusted to below 2.5, and the mixture was stirred at 100 rpm for 30 minutes to obtain a corn slurry hydrolyzate.

[0031] (2) The corn syrup hydrolysate was homogenized by a high-pressure homogenizer. The temperature of the homogenizer was set at 20°C and the pressure was set at 80 MPa. The feed rate of the corn syrup hydrolysate was set at 20 L / min to obtain homogenized corn syrup.

[0032] (3) The homogenized corn slurry is heated to 85° C. After the heating is completed, it is filtered through a 40-mesh filter bag to obtain corn slurry for fermentation.

[0033] Example 2 (1) The corn slurry was heated to 100°C, and then kept warm for 15 minutes. After the heating was completed, the corn slurry was cooled to 70°C. Then, 98% concentrated sulfuric acid was added in a volume ratio of 1:1 to the corn slurry, the pH was adjusted to below 2.5, and the mixture was stirred at 120 rpm for 20 minutes to obtain a corn slurry hydrolyzate.

[0034] (2) The corn syrup hydrolysate was homogenized by a high-pressure homogenizer. The temperature of the homogenizer was set at 15°C and the pressure was set at 60 MPa. The feed rate of the corn syrup hydrolysate was set at 10 L / min to obtain homogenized corn syrup.

[0035] (3) The homogenized corn slurry is heated to 70° C. After the heating is completed, it is filtered through a 60-mesh filter bag to obtain corn slurry for fermentation.

[0036] Example 3 (1) The corn slurry was heated to 130°C, and then kept warm for 20 minutes. After the heating was completed, the corn slurry was cooled to 90°C. Then, 98% concentrated sulfuric acid was added in a volume ratio of 1:4 to corn slurry, the pH was adjusted to below 2.5, and the mixture was stirred at 150 rpm for 40 minutes to obtain a corn slurry hydrolyzate.

[0037] (2) The corn syrup hydrolysate was homogenized by a high-pressure homogenizer. The temperature of the homogenizer was set at 30°C and the pressure was set at 90 MPa. The feed rate of the corn syrup hydrolysate was 30 L / min to obtain homogenized corn syrup.

[0038] (3) The homogenized corn slurry is heated to 90° C. After the heating is completed, the homogenized corn slurry is filtered through a 100-mesh filter bag to obtain corn slurry for fermentation.

[0039] Comparative Example 1 Compared with Example 1, no homogenization treatment is performed, and the remaining steps are the same as Example 1.

[0040] Comparative Example 2 Compared with Example 1, the feed rate in step (2) was changed to 40 L / min, and the remaining steps were the same as in Example 1.

[0041] Comparative Example 3 Compared with Example 1, the homogenization pressure in step (2) is reduced to 40 MPa, and the remaining steps are the same as in Example 1.

[0042] Comparative Example 4 Compared with Example 1, the homogenization temperature in step (2) was lowered to 10° C., and the remaining steps were the same as in Example 1.

[0043] Comparative Example 5 Compared with Example 1, the homogenization pressure in step (2) was increased to 100 MPa, and the remaining steps were the same as in Example 1.

[0044] Experimental Example 1 The corn syrup hydrolyzate and corn syrup for fermentation in Example 1 were examined under a microscope. Microscopic examination steps: The corn syrup hydrolyzate and corn syrup for fermentation were respectively coated on a glass slide and heated to fix, and then crystal violet was added for staining for 1 minute, and then rinsed with deionized water to remove the floating color. The water flow during the rinsing process should not be too fast to avoid damaging the smear; excess water was absorbed with filter paper, and a drop of cedar oil was added, and observation was performed under a microscope. The microscope eyepiece was 10 times, and the objective lens was 100 times. Figure 1 As shown, microscopic examination revealed that the walls of the bacteria in the corn slurry were largely broken after homogenization, and it was difficult to find the complete bacterial morphology under microscopic examination. This shows that the method of the present invention destroys the microbial bacteria in the fermentation corn slurry, so that the obtained fermentation corn slurry is free of bacterial contamination.

[0045] The corn steep liquor hydrolyzate and the corn steep liquor for fermentation in Example 1 were compared in state. Figure 2 As shown, there are many insoluble impurities before homogenization, and the impurities are largely broken and dissolved after homogenization, and the corn steep liquor is mixed evenly. This shows that the present invention can better process corn steep liquor, which is conducive to the use of corn steep liquor in fermentation.

[0046] Experimental Example 2 The fermentation corn steep liquor prepared in Example 1 is used to ferment lysine, and the steps are as follows: (1) Prepare the first-level seed tank culture medium: Dissolve 450g of beet molasses, 2g of ferrous sulfate, 2g of manganese sulfate, 40g of potassium dihydrogen phosphate, 200g of corn syrup for fermentation, 350g of ammonium sulfate, 15mg of copper sulfate, 15mg of zinc sulfate, 50mg of biotin and 2ml of defoamer in water, and make up to 10.5L in a 30L fermentation tank. Sterilize at 121℃ for 20min. Weigh 1kg of glucose powder and 20g of magnesium sulfate, dissolve in water, and make up to 1.5L in a fed-addition tank. Wrap the plug with gauze and kraft paper, and sterilize in an autoclave at 121℃ for 20min.

[0047] (2) After sterilization, add the liquid in the feed tank into the tank through a peristaltic pump. Set the temperature to 32°C, pH 7.0, stirring to 600r, tank pressure to 0.1Mpa, and air volume to 7.5L / min. Maintain stability for 10 minutes and then calibrate the dissolved oxygen to 100%. Pour 500mL of lysine glutathione seeds into the fermentation tank through the inoculation port under the protection of the flame circle, set the stirring to 300r, air volume to 7.5L / min, and tank pressure to 0.05Mpa. When the dissolved oxygen decreases during the fermentation process, increase the speed and air volume to maintain the dissolved oxygen at 30-40%. Start OD detection after 10 hours, and detect once every 2 hours. After 24 hours, the OD is 0.6 and the pressure is maintained.

[0048] (3) Preparation of large tank culture medium: Dissolve 2.5 g of ferrous sulfate, 2.5 g of manganese sulfate, 15 g of potassium dihydrogen phosphate, 300 g of ammonium sulfate, 15 mg of copper sulfate, 15 mg of zinc sulfate, 40 mg of biotin, 200 g of corn syrup for fermentation, 300 g of beet molasses, 10 g of betaine, 15 g of magnesium sulfate and 2 ml of defoaming agent in water, make up the volume to 11 L in a 50 L fermentation tank, and sterilize at 121 °C for 20 min.

[0049] (4) Prepare the feed material: 2g ferrous sulfate, 2g manganese sulfate, 45g phosphoric acid, 55g magnesium sulfate, 100mg copper sulfate, 100mg zinc sulfate, 40mg biotin, 400g corn syrup for fermentation, 450g beet molasses, 60g betaine and 2ml defoamer, dissolve in water, make up to 6L in the feed tank, and sterilize at 121℃ for 20min. Take the production sugar solution and ammonium sulfate from the workshop and sterilize at 121℃ for 20min.

[0050] (5) After sterilization, add 300g of sugar solution into the fermentation tank through a peristaltic pump. Transfer the bacterial solution from the first-level seed tank to the large tank through the transfer pipe, with a transfer volume of 2.5L. Set the temperature to 37℃, pH 6.9, stirring 300r, tank pressure 0.05Mpa, and air volume 0.5m 3 / h, calibrate the dissolved oxygen to 100% and start the fermentation control tank.

[0051] After the pH rises, start adding sugar solution, small materials, and ammonium sulfate. The amount of sugar solution added before 24 hours: small materials = 8:1 (v / v), and the addition ratio after 24 hours is 9:1 (v / v). During the fermentation process, control the residual sugar to 0.5-1.0%, ammonia nitrogen to 0.3-0.4%, and dissolved oxygen to more than 30%. As the fermentation proceeds, when the dissolved oxygen is lower than 30%, gradually increase the speed, air volume, and tank pressure to maintain the dissolved oxygen above 30% until the highest condition. When the dissolved oxygen is high in the late fermentation stage, gradually reduce the speed and air volume until the fermentation is completed. After 48 hours of fermentation, the tank is removed from the tank and the lysine content and conversion rate in the tank are measured.

[0052] Experimental Example 3 The difference from Experimental Example 2 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 1.

[0053] Experimental Example 4 The difference from Experimental Example 2 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 2.

[0054] Experimental Example 5 The difference from Experimental Example 2 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 3.

[0055] Experimental Example 6 The difference from Experimental Example 2 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 4.

[0056] Experimental Example 7 The difference from Experimental Example 2 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 5.

[0057] Experimental Example 8 The lysine content was determined by titration.

[0058] The conversion rate was calculated based on the following formula: sugar-acid conversion rate = acid production / total sugar consumption × 100%, acid production = acid content × lower tank volume, and total sugar consumption was the actual mass of glucose consumed.

[0059] The results of the measured lysine content and conversion rate are shown in Table 1.

[0060] Table 1 Comparison of lysine content and conversion rate in each group of fermentation

[0061] Lysine fermentation has a relatively mature fermentation process. During the experiment, it was found that it was difficult to significantly improve the fermentation level by improving the formula or process. However, as shown in Table 1, in the process of fermenting lysine, the lysine content and conversion rate of the fermented corn steep liquor prepared in Example 1 were improved compared with the fermented corn steep liquor prepared in Comparative Examples 1-5, indicating that the fermented corn steep liquor obtained by the preparation process set by the present invention has the effect of increasing the yield of lysine.

[0062] Experimental Example 9 The fermentation corn steep liquor prepared in Example 1 is used to ferment and produce L-isoleucine, and the steps are as follows: (1) Prepare the first-level seed tank culture medium: 0.8g ferrous sulfate, 0.5g manganese sulfate, 60g potassium dihydrogen phosphate, 600g corn syrup for fermentation, 18mg copper sulfate, 12mg zinc sulfate, 0.16g biotin and 2ml defoamer, dissolve in water, and make up to 10.5L in a 30L fermentation tank. Sterilize at 121℃ for 20min. Weigh 1kg glucose powder, 23g magnesium sulfate and 400g beet molasses, dissolve in water, and make up to 1.5L in a fed-addition tank. Wrap the plug with gauze and kraft paper, and sterilize in an autoclave at 121℃ for 20min.

[0063] (2) After sterilization, add the liquid in the feed tank into the tank through a peristaltic pump. Set the temperature to 30°C, pH 7.4, stirring to 600r, tank pressure to 0.05Mpa, and air volume to 12L / min. Maintain stability for 5 minutes and then calibrate the dissolved oxygen to 100%. Under the protection of the flame circle, pour 50mL of Corynebacterium glutamicum seeds into the fermentation tank through the inoculation port, set stirring to 300r, air volume to 6L / min, and tank pressure to 0.05. When the dissolved oxygen decreases during the fermentation process, increase the speed and air volume to maintain the dissolved oxygen at 30-40%. Start OD detection at 8h, and detect once every 2h. After 22h, the OD value is 0.653, and the pressure is maintained.

[0064] (3) Prepare large tank culture medium: 50 mg of ferrous sulfate, 70 mg of manganese sulfate, 20 g of potassium dihydrogen phosphate, 60 g of ammonium sulfate, 12 mg of copper sulfate, 14 mg of zinc sulfate, 0.15 g of biotin and 2 ml of defoamer, dissolve in water, make up to 18 L in a 50 L fermenter, and sterilize at 121 ° C for 20 min. Weigh 4 kg of glucose powder, 19 g of magnesium sulfate and 430 g of beet molasses, dissolve in water, make up to 6 L in a fed-addition tank, wrap the plug with gauze and kraft paper, and sterilize in an autoclave at 121 ° C for 20 min.

[0065] (4) After sterilization, add the liquid in the feed tank to the tank through a peristaltic pump. Set the temperature to 32°C, pH 7.4, stirring 650r, tank pressure 0.05Mpa, and air volume 1m³ / h. After maintaining stability for 5 minutes, calibrate the dissolved oxygen to 100%. Transfer the bacterial liquid in the first-level seed tank to the large tank through the transfer pipe, with a transfer volume of 4L. Set the stirring to 300r, tank pressure 0.05, and ventilation ratio 0.3, and start fermentation tank control.

[0066] (5) During the fermentation process, the sugar was initially measured at 12g / dL. As the fermentation progressed, when the dissolved oxygen was lower than 20%, the speed was gradually increased to maintain the dissolved oxygen at 20-30%. After the speed was increased to 350r, the ventilation ratio was increased by 0.1. Next, the speed was gradually increased to 400r, and the ventilation ratio was increased to 0.4, and so on, until the highest condition was reached. When the dissolved oxygen was high in the late fermentation period, the speed was gradually reduced, and the ventilation ratio remained unchanged until the fermentation was completed. After 21h of fermentation, the pH rose. After 10min of rising, the L-isoleucine content and conversion rate were measured in the tank.

[0067] Experimental Example 10 The difference from Experimental Example 9 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 1.

[0068] Experimental Example 11 The difference from Experimental Example 9 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 2.

[0069] Experimental Example 12 The difference from Experimental Example 9 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 3.

[0070] Experimental Example 13 The difference from Experimental Example 9 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 4.

[0071] Experimental Example 14 The difference from Experimental Example 9 is that the corn steep liquor for fermentation prepared in Example 1 is replaced by the corn steep liquor for fermentation prepared in Comparative Example 5.

[0072] Experimental Example 15 The content of L-isoleucine was determined by HPLC.

[0073] The conversion rate was calculated based on the following formula: sugar-acid conversion rate = acid production / total sugar consumption × 100%, acid production = acid content × lower tank volume, and total sugar consumption was the actual mass of glucose consumed.

[0074] The results of the measured isoleucine content and conversion rate are shown in Table 2.

[0075] Table 2 Comparison of L-isoleucine content and conversion rate in each group of fermentation

[0076] Isoleucine fermentation itself produces low acid and is a low conversion rate fermentation. Compared with its amino acids, it is more difficult to significantly increase the conversion rate, and a small increase in the conversion rate is a large change in the experiment or production process. As can be seen from the results in Table 2, in the process of fermentation to produce isoleucine, the fermentation of corn steep liquor prepared in Example 1 to produce L-isoleucine has an improved L-isoleucine content and conversion rate compared to the fermentation corn steep liquor prepared in Comparative Examples 1-5, indicating that the fermentation corn steep liquor obtained by the preparation process set by the present invention has the effect of increasing the yield of L-isoleucine.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing corn steep liquor for fermentation, characterized in that: The method comprises the following steps: hydrolyzing corn syrup, homogenizing the hydrolyzed corn syrup, and then heating and filtering the homogenized corn syrup to obtain corn syrup for fermentation; The step of hydrolyzing the corn slurry comprises: heating the corn slurry, keeping the temperature after heating, cooling the corn slurry after keeping the temperature, adding concentrated sulfuric acid, adjusting the pH to below 2.5, stirring, and obtaining a corn slurry hydrolyzate; The homogenization conditions include: temperature 15-30°C, pressure 60-90Mpa, and feed rate 10-30L / min.

2. The preparation method according to claim 1, characterized in that The corn steep liquor is heated to 100-130° C., and the heat preservation time is 10-30 minutes.

3. The preparation method according to claim 1, characterized in that: The corn steep liquor is cooled to 70-90°C.

4. The preparation method according to claim 1, characterized in that: The volume ratio of the concentrated sulfuric acid to the corn steep liquor is 1:1-4.

5. The preparation method according to claim 1, characterized in that: The temperature of the homogenized corn steep liquor is raised to 70-90°C.

6. The preparation method according to claim 1, characterized in that: The pore size of the filtration is 30-50 meshes.

7. Corn steep liquor for fermentation prepared by the preparation method according to any one of claims 1 to 6.

8. Use of corn steep liquor for fermentation prepared by the preparation method according to any one of claims 1 to 6 in preparing fermentation medium.

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